This invention relates to apparatus for directing coordinated movement of paralyzed muscles and exercising them to reverse the atrophy resulting from the inactivity which follows the onset of a paralyzing occurrence. A typical prior art device is shown, for instance, in Petrofsky et al Ser. No. 417,935, filed Sept. 14, 1982. Through the use of such devices it has been found possible to exercise paralyzed muscles in a controlled fashion, even after years of inactivity. Such systems operate by applying electrical stimulation to muscles which have been cut off from communication with the brain, as a result of spinal cord damage, stroke, or other neuromuscular conditions involving upper motoneuron dysfunction.
A system as taught by Petrofsky et al includes a microprocessor for generating digital commands indicating a desired motion by a paralyzed limb, a digital-to-analog converter, a plurality of stimulation electrodes, a sensor for sensing motion of the stimulated limb, and an analog-to-digital converter which receives the output of the position sensor and converts it to digital form for use by the microprocessor. The system also includes dynamic load means which apply a resisting force to the paralyzed limb during stimulated motion thereof.
While a system as taught by Petrofsky et al is able to perform numerous complex mathematical manipulations as appropriate for carrying out a variety of sophisticated exercise routines, there exists a need for a simpler device which need not be programmed and which is able to conduct a specified exercise routine for a paralyzed limb, such as a human leg.